FZD蛋白家族的起源与演化分析

The origin and evolution of FZD protein family

FZD(Frizzled)蛋白家族是Wnt信号通路的跨膜受体,在动物发育过程中起着非常关键的作用.通过对不同物种(从单细胞动物到哺乳动物)基因组中FZD家族基因的检索,发现FZD蛋白家族起源于早期的、与海绵动物具有共同祖先的后生动物.进化分析结果表明,FZD蛋白家族分为4个亚家族:FZD1/2/3/4/6/7亚家族、FZD5/8亚家族、FZD4亚家族和FZD9/10亚家族;不同亚家族之间的motif组成不同,但在C端都含有一个保守的KTXXXW motif.进化速率分析结果表明,尽管FZD蛋白家族成员在演化过程中受到较强的纯化选择,但是在其基因发生复制或motif组成变化的分支上仍有正选择的作用.该结果可为进一步理解FZD蛋白家族的起源与演化动态提供一定的参考.

FZDs （Frizzleds）, astransmembrane receptors in the Wnt signaling pathway, play pivotal role in animal development. Through retrieved FZD protein family members from the genomes of unicellular animals to mammals, we found that FZD derived from early metazoan which has the common ancestor of sponge （Amphimedon queenslandica）. Our results also showed that the FZD protein family could be divided into four subfamilies, FZD1/2/3/4/6/7 subfamily, FZDS/8 subfamily, FZD4 subfamily and FZD9/10 subfamily. Although different motif components between different subfamilies are different, a conserved KTXXXW motif has been found in all four kinds of FZD proteins. The results of selection pressure suggested that the FZD proteins underwent positive selective in the branches of gene duplication and motif component changes, although they were subject to a strong purifying selection. This result help us to get more understanding of the origin and evolutionary dynamics of FZD protein family.